The present invention relates to the field of electronic devices, and, more particularly, to voltage regulators and related methods.
Many electronic devices use voltage regulators to convert a base DC voltage to a particular operating voltage for a given component or components. Various types of voltage regulators are available, such as switching regulators, linear regulators, etc. Such voltage regulators can be boost regulators which, as the name implies, provide a higher output voltage than the base voltage, or buck regulators which provide a lower output voltage than the base DC voltage.
One voltage regulator which is commonly used with microprocessors is the multiphase switching buck converter. A multiphase DC-to-DC converter includes multiple output stages with inductors that are switched on and off in separate phases. As a result, the switching load is distributed over several phases which reduces switching transients compared with traditional switching regulators, plus smaller inductors may be used and fewer input capacitors may also be required. The multiphase architecture also reduces peak inductor currents, thereby enhancing efficiency.
One example of a multiphase DC voltage regulator is disclosed in U.S. Pat. No. 5,959,441 to Brown. In particular, this patent is directed to a multiphase direct current (DC) regulator which uses voltage mode control to provide a regulated voltage and provide current equalization between the phases. The regulator includes a voltage mode control circuit receiving an indication voltage level indicative of the amount of current supplied from the DC power source to an inductor of a first phase. The voltage mode control circuit provides a first control signal to a switching circuit based upon the indication voltage level, and the switching circuit provides a switching signal to a switch. The switch controls the amount of current from the DC power source that is supplied to a second inductor of a second phase based upon the switching signal. Another similar example of a multiphase DC voltage regulator is provided in U.S. Pat. No. 5,959,441 to Brown.
In such multiphase regulators, it is typically desired to monitor the various phase currents to perform such functions as fault detection, current balancing, etc. Such current monitoring is typically done by measuring the current present at the output of each output stage. Yet, unless the components of the output stages are carefully matched and calibrated, the component tolerances and/or temperature compensation responses of such components will adversely affect the precision with which these currents can be measured.
In view of the foregoing background, it is therefore an object of the present invention to provide a multiphase switching regulator and related methods which allow for relatively precise output phase current measurement.
This and other objects, features, and advantages in accordance with the present invention are provided by an electronic device which may include a circuit board, at least one load circuit carried by the circuit board, and a power distribution conductor carried by the circuit board and connected to the at least one load circuit. The electronic device may also include a multiphase switching regulator including a plurality of output stages connected to the power distribution conductor, and a controller for controlling the output stages based upon respective phase currents. The respective phase currents may be derived from corresponding voltage drops across the power distribution conductor and a matrix of resistivity values.
More particularly, the electronic device may also include at least one analog-to-digital converter for converting the corresponding voltage drops to digital values, and the matrix of resistivity values may be a matrix of digital resistivity values. Thus, the controller may include digital processing circuitry for deriving the respective phase currents based upon these digital values. The controller may also include a memory for storing the matrix of digital resistivity values.
As such, the multiphase switching regulator may advantageously utilize digital processing to determine the phase currents, while reducing the potential inaccuracies associated with prior art current monitoring approaches. That is, because the controller determines the phase currents based upon the respective voltage drops across the power distribution conductor, the effects of varying component tolerances can be significantly reduced. Thus, specially matched or calibrated components, such as the FETs used in the output stages, need not be used in many applications. Accordingly, precise current derivation may be obtained while leaving more error budget in the circuit design for items such as load-line indeterminacy, for example.
Further still, the electronic device may also include a resistivity measurement structure connected to the power distribution conductor and the controller. As such, the controller may generate the matrix of resistivity values based upon baseline resistivity values and resistivity values from the resistivity measurement structure. For example, the baseline resistivity values could be measured and stored during manufacture, and measurements taken from the resistivity measurement structure may be taken during operation and used to adjust the baseline values based upon resistivity fluctuations caused by temperature, aging, etc. By way of example, the resistivity measurement structure may be at least one Van der Pauw measurement structure.
Moreover, the multiphase switching regulator may be a pulse width modulated switching regulator. The multiphase switching regulator may also be a multiphase buck switching regulator, for example. Further, each output stage may include at least one output and an inductor connected thereto, and the matrix of resistivity values may be based upon resistivities from the inductors to the at least one load circuit (i.e., the resistivities of the power distribution conductor).
Additionally, the circuit board may include at least one dielectric layer and at least one conductive layer thereon, and the at least one load circuit may be a microprocessor, for example. The electronic device may also include a battery connected to the multiphase switching regulator.
A method aspect of the invention is for supplying power to at least one load circuit carried by a circuit board using a power distribution conductor also carried by the circuit board and connected to the at least one load circuit. The method may include connecting a plurality of output stages to the power distribution conductor, and determining respective voltage drops across the power distribution conductor for the output stages. Moreover, phase currents may be derived for the output stages based upon the voltage drops and a matrix of resistivity values, and the output stages may be controlled to provide multiphase switching based upon the derived phase currents.